Plant room

Hi

Recently I was asked to guide some trainees on how to go about planning a plant/machine room for a refrigeration plant. The example I took was planning the machine room for an ammonia recirculation plant, where I highlighted on the room size and ventilation requirements as per the health and safety regulations and then the considerations of piping, placing the hardware etc were discussed.

However, I believe when a professional plans this, there will certainly be a considerable amount of thoughts going into this based on the experiences on practical/maintenance aspects. Could you cite some of those

Cheers

simon

You can refer to ASHRAE handbook.

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Originally Posted by SimonBrown

Hi

Recently I was asked to guide some trainees on how to go about planning a plant/machine room for a refrigeration plant. The example I took was planning the machine room for an ammonia recirculation plant, where I highlighted on the room size and ventilation requirements as per the health and safety regulations and then the considerations of piping, placing the hardware etc were discussed.

However, I believe when a professional plans this, there will certainly be a considerable amount of thoughts going into this based on the experiences on practical/maintenance aspects. Could you cite some of those

Cheers

simon

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I could refer you to BSEN378:D

Consider 1.2m clear space aroung each peice of equipment, where access is needed (most vessels are designed to be accessed from the frount and sides, compressor units from all sides). Lifting beams are required directly above the compressor units to removing motors and compressors, it is usual to carry the beam out through the plant room door, 2m wide or more.

Rubber matts and ventilation that has a manual switch and leak detection with a manual, key type overide and all good and necessary inclusions.
Also the room has to be fire rated (dependant on building control in your area) so all pipe holes ect should be sealed. Sealing is also necessar to help contain the gas in the event of a leak.

Hope this helps.

Kind Regards Andy:)

An article explaiing this point states
Ventilation is typically needed
1. For Room temp control
2. Ammonia Evaucation in case of leak

ANSI/ASHRAE 15 & ANSI/ IIAR-2 state that as long as vent requirements as per these codes are satisfied, the machne room is classifed as non hazardous location by Natioanl Electric Code ( NEC)
If such is not provided, all elec. equipment must comply to Class I diV 2 requirements.

Some other codes specify the 12 Air changes per hour as standard
ANSI/Ashrae-15 specifies
Cfm= 100 x Sq root of Pounds of Ammonia ( System Charge)

- 1.5 cfm. sq ft ( min vent rate) or max 10 cfm. sq ft of machine area ( subject o min of 2000 cfm)

This is the most stringent code though.

Use of Upblast high velocity discharge fans is preferred for effective dispersion of Nh3
I have even seen use of special hood & fans for dispersion of Ammonia.

Now a days, it is recommended to have two receivers so that in case of failure of one, other can be filled up.

Local govts may have some issues as well.

Is room containment a requirement in the code or law ? I noticed in my country, some machine rooms (where the compressors and vessels are located) are not walled in (meaning some side do not have any walls). The engineer stated that they do not want to contain the ammonia gas in the room as this is a safety concern. They wanted to install mist nozzles to wash down the gas with water. There is short bunded wall around the vessels sized to contain the volume of the liquid. Is this correct ?